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ARRL Propagation Bulletin ARLP044 (1997)

ARLP044 Propagation de K7VVV

Propagation Forecast Bulletin 44  ARLP044
From Tad Cook, K7VVV
Seattle, WA  October 31, 1997
To all radio amateurs

ARLP044 Propagation de K7VVV

Disturbed conditions forecast for last weekend hit quite hard.  A
coronal mass ejection a few days earlier caused the planetary A
index to hit 25 last Friday, 19 on Saturday and 14 on Sunday.  This
caused HF havoc during the CQ Worldwide DX Contest.

Last week we saw the average solar flux drop a few points, and the
average sunspot number decline by 10.  At the same time the average
flux for the previous 90 days went up by one point from 86 to 87,
and the solar flux was below this average for six out of the seven

This weekend is the ARRL CW Sweepstakes, and conditions for this
domestic contest should be quite a bit better.  Conditions are
expected to be quiet to unsettled, with solar flux climbing from 90
to 95.

Northwest Research Associates has an interesting web site devoted to
space weather, including charts of 10.7 cm solar flux, effective
sunspot numbers and geomagnetic indices.  Check it out at

Sunspot Numbers for October 23 through 29 were 0, 11, 13, 14, 44, 50
and 41 with a mean of 24.7.  10.7 cm flux was 79.7, 78.6, 81.4, 82,
84.4, 85.5 and 87.2, with a mean of 82.7, and estimated planetary A
indices were 6, 25, 19, 14, 15, 13, and 10, with a mean of 14.6.

Here are some projections for domestic paths for this contest

From California to the Northeast United States check 80 meters 2330-
1230z, 40 meters 2130-0300z and 0630-1500z, 20 meters 1500-2200z,
and possibly 15 meters around 1800-1900z.

From Southeast United States to California check 80 meters 0000-
1300z, 40 meters around the clock, with the strongest signals from
0130-0300z and 0630-1130z, and 20 meters 1530-2200z.

From Ohio to Texas, check 80 meters 2130-1400z, 40 meters around the
clock with the least stable conditions around 0500-0600z and the
strongest signals from 0000-0200z and 0700-1130z.  Check 20 meters

From Seattle to the central U.S., check 80 meters 2300-1500z, 40
meters around the clock, with strongest signals 0100-0500z and 0800-
1300z, and 20 meters 1530-2330z.  15 meters may open 1800-2130z, and
10 meters might open 1900-2030z.

From central U.S. to Hawaii, check 80 meters 0330-1400z, 40 meters
0200-1500z, 20 meters around 1600z and 1700-0000z and 0130-0230z.
15 meters looks very good 1730-2330z.


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